Dot printers that create dots on printing media to print images are widely used as an output device of images generated by computers and images taken by digital cameras. The dot printer, for example, an inkjet printer, has a print head for dot formation on a printing medium and creates dots with a relative positional shift of the print head to the printing medium to complete a printed image.
The dot printer does not sequentially create dots from one end of an image. In a printing device that scans a print head relative to a printing medium and creates dots to form rasters or dot lines and complete a printed image, for the enhanced picture quality, each raster is not formed by only one scan but is completed by multiple scans. In the technique of completing each raster by multiple scans of the print head, the sequence of dots on rasters of an image may not be consistent with the order of dot formation. In the dot printer that creates dots in a different order from the sequence of dots on rasters of one image, one proposed technique determines the dot on-off state of respective pixels included in the image and rearranges dot data representing the determination results of the dot on-off state in the order of dot formation (see, for example, Japanese Patent Laid-Open Gazette No. 2002-292850).
The rearrangement of the dot data in the order of dot formation by this prior art technique, however, takes a relatively long time. This time-consuming rearrangement is one factor of interference with the high-speed image printing.
The object of the invention is thus to eliminate the drawbacks of the prior art technique and to provide a technique that rationally rearranges dot data representing determination results of dot on-off state in an order of dot formation and thereby ensures high-speed image printing.